Thanks for reply. I think I confused you. I just want tomato not to connect the network when the line dropped without my request. Says, when there is no connection, tomato doesn't need to reconnect (redial).

It's not Tomato that's going to try, and connect it's your computer that's doing it.
Try calling this person before you try to connect to see if they are using the account.
Also you might think about getting your own account, saves a lot of head aches.

But I just take a test on the connection scheme which I don't understand by which situation it reconnects. I tried disconnected manually before I open up my download manager software, it stops reconnect even I start the download nor refreshing websites. I made another test which I started the download and soft disconnected the network in tomato GUI, it reconnects with no buttons clicked in the GUI.

What you're asking is a way to set it so that when you are disconnects, it won't reconnect until you manually tell it to?

I think the easiest way to get it to behave like that:

Set Connect Mode to "Keep Alive" (NOT "connect on demand")

Set Check Interval to an arbitrarily high number. 86400 is the largest the gui will let you enter — that's 24 hours.

When you lose the connection, Tomato will wait the specified amount of time before trying to reconnect — regardless of what traffic is on your network. When you ACTUALLY want to reconnect, presumably sooner than that, go to the gui status page and hit the connect button (… or if it still shows as connected, or as reconnecting, hit disconnect then connect to reset it.)

But honestly, I agree with Ronnie: this connection sharing scheme sounds like a real headache.